Crowding Ratio in Young Normally Sighted Children

Purpose: To determine normal values of the crowding ratio (CR) in children. Methods: Of 62 normally sighted primary school children aged 4-12 years old the CR was determined both for distance and near vision. The examinations were performed using commonly available test charts based on the LEA symbols. Results: At near, the CR was significantly better than at distance and for all ages < 2.0. The upper limit of the CR at distance was < 2.0 from age six. Conclusion: With commonly available tests the CR can easily be determined in school age children. For children > 6 years of age, a CR > 2.0 (i. e. at least 3 lines difference between the result of a single optotype acuity test and a line acuity test) is suspicious and warrants further investigation. It may, for example, be a sign of cerebral visual impairment (CVI).